Enzymatic synthesis of glutathione.

The formation of glutathione in liver slices, in liver homogenates, and in extracts of acetone-dried pigeon liver and the effect of adenosinetriphosphate on this reaction have previously been demonstrated in this laboratory (l-3). In the present report, the synthesis of glutathione which is catalyzed by soluble liver enzymes is described in greater detail. The reaction occurs anaerobically when the constituent amino acids of the tripeptide, phosphate, magnesium, and an adenine nucleotide are present. A net synthesis of the tripeptide can be demonstrated under these conditions. The evidence suggests that the energy required for the synthetic process can be furnished by the cleavage of the pyrophosphate moiety of adenine nucleotides, in agreement with the concepts developed by Lipmann (4). Naturally occurring peptides therefore appear to be synthesized by a mechanism similar to that for the “peptidic” model compounds which have been studied previously by various investigators (5-9). As in earlier experiments, glutathione synthesis has been measured by following the incorporation of C14-glycine and in some cases of labeled glutamic acid into the tripeptide. In a few experiments, glutathione was assayed enzymatically by the glyoxalase method.